Power control for ACK/NACK formats with carrier aggregation

ABSTRACT

A system and method for determining a Physical Uplink Control Channel (PUCCH) power control parameter h(n CQI ,n HARQ ) for two Carrier Aggregated (CA) PUCCH formats—PUCCH format 3 and channel selection. The value of h(n CQI ,n HARQ ) may be based on only a linear function of n HARQ  for both of the CA PUCCH formats. Based on the CA PUCCH format configured for the User Equipment (UE), the e-Node B (eNB) may instruct the UE to select or apply a specific linear function of n HARQ  as a value for the power control parameter h(n CQI ,n HARQ ), so as to enable the UE to more accurately establish transmit power of its PUCCH signal. Values for another PUCCH power control parameter—Δ F     —     PUCCH (F)—are also provided for use with PUCCH format 3. A new offset parameter may be signaled for each PUCCH format that has transmit diversity configured.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending U.S. patent applicationSer. No. 13/078,212 filed Apr. 1, 2011, which claims the prioritybenefit under 35 U.S.C. §119(e) of U.S. Provisional Application No.61/411,527 filed Nov. 9, 2010, and U.S. Provisional Application No.61/412,068 filed Nov. 10, 2010, the disclosures of which areincorporated herein by reference in their entireties.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

REFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTINGCOMPACT DISC APPENDIX

Not Applicable

BACKGROUND

The present invention relates to power control in wireless communicationsystems. More particularly, and not by way of limitation, the presentinvention is directed to a system and method for controlling transmitpower of a Physical Uplink Control Channel (PUCCH) signal in a cellularwireless network with Carrier Aggregation (CA).

In a wireless communication system (e.g., a third generation (3G) or aLong Term Evolution (LTE) fourth generation (4G) cellular telephonenetwork), a base station (e.g., an evolved Node-B or eNodeB (eNB) or asimilar entity) may transmit wireless channel resource allocationinformation to a mobile handset or User Equipment (UE) via a downlinkcontrol signal, such as the Physical Downlink Control Channel (PDCCH)signal in Third Generation Partnership Project (3GPP) 3G and 4Gnetworks. Modern cellular networks use Hybrid Automatic Repeat Request(HARQ) in which, after receiving this PDCCH downlink transmission (i.e.,transmission from a base station to a mobile device), the UE may attemptto decode it and report to the base station whether the decoding wassuccessful (ACK or Acknowledge) or not (NACK or Negative Acknowledge).Such reporting may be performed by the UE using an uplink transmission(i.e., transmission from a mobile device to a base station in a cellularnetwork), such as the Physical Uplink Control Channel (PUCCH) signal inthe 3G and 4G networks. Thus, the uplink control signal PUCCH from themobile terminal to the base station can include hybrid-ARQacknowledgements (ACK/NACK) for received downlink data. The PUCCH mayalso additionally include terminal reports (e.g., in the form of one ormore Channel Quality Indicator (CQI) bits) related to the downlinkchannel conditions. Such reports may be used by the base station toassist it in future downlink scheduling of the mobile handset. The PUCCHmay further include scheduling requests by the UE, indicating that themobile terminal or UE needs uplink resources for uplink datatransmissions.

The general operations of the LTE physical channels are described invarious Evolved Universal Terrestrial Radio Access (E-UTRA)specifications such as, for example, 3GPP's Technical Specifications(TS) 36.201 (“Physical Layer: General Description”), 36.211 (“PhysicalChannels and Modulation”), 36.212 (“Multiplexing and Channel Coding”),36.213 (“Physical Layer Procedures”), and 36.214 (“PhysicalLayer—Measurements”). These specifications may be consulted foradditional reference and are incorporated herein by reference.

It is observed here that LTE Release-8 (Rel-8) now has been standardizedto support operating bandwidths of up to 20 MHz. However, in order tomeet International Mobile Telecommunications (IMT)-Advancedrequirements, 3GPP has initiated work on LTE Release-10 (Rel-10) (“LTEAdvanced”) to support bandwidths larger than 20 MHz. One importantrequirement in LTE Rel-10 is to assure backward compatibility with LTERel-8. This includes spectrum compatibility, i.e., an LTE Rel-10carrier, wider than 20 MHz, should appear as a number of (smaller) LTEcarriers to an LTE Rel-8 terminal. Each such smaller carrier can bereferred to as a Component Carrier (CC). It is observed here that duringinitial deployments of LTE Rel-10, the number of LTE Rel-10-capableterminals may be smaller compared to many LTE legacy terminals (e.g.,Rel-8 terminals). Therefore, it is necessary to assure an efficient useof a wide (Rel-10) carrier also for legacy terminals. In other words, itshould be possible to implement carriers where legacy terminals can bescheduled in all parts of the wideband LTE Rel-10 carrier. One way toobtain this efficient usage is by means of Carrier Aggregation (CA). CAimplies that an LTE Rel-10 terminal can receive multiple CCs, where eachCC has, or at least the possibility to have, the same structure as anRel-8 carrier. FIG. 1 illustrates the principle of CC aggregation. Asshown in FIG. 1, an operating bandwidth of 100 MHz (indicated byreference numeral “2”) in Rel-10 may be constructed by the aggregationof five (contiguous, for simplicity) smaller bandwidths of 20 MHz (incompliance with Rel-8 requirements) as indicated by reference numerals“4” through “8”. It is noted here that Rel-10 supports aggregation of upto five carriers, each with a bandwidth of up to 20 MHz. Thus, forexample, if desired, carrier aggregation in Rel-10 also may be used toaggregate two carriers of 5 MHz bandwidth each. The carrier aggregationin uplink and downlink may thus support higher data rates than possiblein legacy communication systems (i.e., UE's operating under 3GPP Rel-8or below). UE's capable of operating only over a single Downlink/Uplink(DL/UL) pair may be referred to as “Legacy UE's”, whereas UE's capableof operating over multiple DL/UL CCs may be referred to as“Advanced-UE's”.

The number of aggregated CCs as well as the bandwidth of the individualCC may be different for uplink and downlink. A “symmetric configuration”refers to the case where the number of CCs in downlink and uplink is thesame, whereas an “asymmetric configuration” refers to the case that thenumber of CCs is different in uplink and downlink. It is important tonote that the number of CCs configured in the network may be differentfrom the number of CCs seen by a terminal (or UE): A terminal may, forexample, support more downlink CCs than uplink CCs, even though thenetwork offers the same number of uplink and downlink CCs. The linkbetween DL CCs and UL CCs can be UE-specific.

Scheduling of a CC is done on the PDCCH via downlink assignments.Control information on the PDCCH may be formatted as a Downlink ControlInformation (DCI) message. In Rel-8, a terminal only operates with oneDL and one UL CC. Therefore, the association between DL assignment, ULgrants, and the corresponding DL and UL CCs is clear in Rel-8. However,in Rel-10, two modes of CA need to be distinguished: The first mode isvery similar to the operation of multiple Rel-8 terminals—i.e., a DLassignment or UL grant contained in a DCI message transmitted on a CC iseither valid for the DL CC itself or for associated (either viacell-specific or UE-specific linking) UL CC. A second mode of operationaugments a DCI message with the Carrier Indicator Field (CIF). A DCImessage containing a DL assignment with CIF is valid for that DL CCindicated with CIF and a DCI containing an UL grant with CIF is validfor the indicated UL CC.

It is observed here that it is desirable to control transmit power for atransmit signal (e.g., a PUCCH signal to be transmitted from a UE to abase station) while exchanging data between a base station (BS) and aUE. In particular, transmit power control of an uplink channel isimportant in terms of power consumption of the UE and servicereliability. In uplink transmission, if a transmit power is too weak,the BS cannot receive a transmit signal of the UE. On the other hand, ifthe transmit power is too strong, the transmit signal may act asinterference to a transmit signal of another UE, and may increasebattery consumption of the UE transmitting such a powerful signal.

DCI messages for downlink assignments (of uplink resources) contain,among others, resource block assignment, modulation and coding schemerelated parameters, HARQ redundancy version, etc. In addition to thoseparameters that relate to the actual downlink transmission, most DCIformats for downlink assignments also contain a bit field for TransmitPower Control (TPC) commands. These TPC commands may be used by eNB tocontrol the uplink power of the corresponding PUCCH that is used totransmit the HARQ feedback (in response to the received DCI message viaPDCCH). More generally, TPC commands are used to control transmit powerof a channel between a base station (BS) and a UE.

Each DL assignment may be scheduled with its own DCI message on thePDCCH. Since Rel-8 DCI formats or formats very similar to Rel-8 are alsoused for Rel-10, each received DCI message in Rel-10 therefore containsa TPC bit field providing an adjustment value for the transmit power forPUCCH. It is observed here that the operating point for all PUCCHformats is common. That is, Rel-8 PUCCH formats 1/1a/1b/2/2a/2b andadditional PUCCH formats in Rel-10—i.e., PUCCH format 3 and channelselection based HARQ feedback schemes—all use the same power controlloop, with the exception of the power control parametersh(n_(CQI),n_(HARQ)) and Δ_(F) _(—) _(PUCCH)(F) (defined below withreference to equation (1)). These parameters at least take into accountdifferent performance and payload sizes for the different PUCCH formats.Therefore these parameters are individually determined per PUCCH format.

In Rel-8, the PUCCH power control is defined as follows:P _(PUCCH)(i)=min{P _(CMAX) ,P ₀ _(—) _(PUCCH) +PL+h(n _(CQI) ,n_(HARQ))+Δ_(F) _(—) _(PUCCH)(F)+g(i)}  (1)In the above equation (1), “P_(PUCCH)(i)” refers to PUCCH transmit powerfor subframe “i” (e.g., a 1 ms subframe in a 10 ms radio frame);“P_(CMAX)” refers to configured maximum transmit power (at UE) for PUCCHCC (e.g., a UL PCC (Uplink Primary CC)); “P₀ _(—) _(PUCCH)” refers todesired PUCCH receive power (at eNB or other similar control node inLTE) signaled by higher layers (in an LTE network); “h(n_(CQI),n_(HARQ))” refers to an offset parameter that depends on the number“n_(CQI)” (≧0) of CQI bits or the number “n_(HARQ)” (≧0) of HARQ bits(in the PUCCH signal to be transmitted by the UE), to retain the sameenergy per information bit; “Δ_(F) _(—) _(PUCCH)(F)” refers to an offsetparameter that depends on the PUCCH format (of the PUCCH signaltransmitted by the UE), to give sufficient room for different receiver(e.g., eNB or other base station) implementation and radio conditions;

$``{{g(i)} = {{g(i)} + {\sum\limits_{m = 0}^{M - 1}\;{\delta_{PUCCH}\left( {i - k_{m}} \right)}}}}"$refers to an accumulated power adjustment value derived from TPC command“δ_(PUCCH)(i)”. The values “M” and “k_(m)” depend on whether theduplexing mode (e.g., the mode of communication between UE and eNB) isFrequency Division Duplex (FDD) or Time Division Duplex (TDD); and “PL”refers to path loss.

It is known that, in Rel-8, PUCCH supports multiple formats such asformat 1, 1a, 1b, 2, 2a, 2b, and a mix of formats 1/1a/1b and 2/2a/2b.These PUCCH formats are used in the following manner: PUCCH format 1uses a single Scheduling Request Indicator (SRI) bit, PUCCH format 1auses a 1-bit ACK/NACK, PUCCH format 1b uses a 2-bit ACK/NACK, PUCCHformat 2 uses periodic CQI, PUCCH format 2a uses periodic CQI with 1-bitACK/NACK, and PUCCH format 2b uses periodic CQI with 2-bit ACK/NACK.

In Rel-8/9, h(n_(CQI),n_(HARQ)) is defined as follows:

a. For PUCCH formats 1, 1a and 1b, h(n_(CQI),n_(HARQ))=0

b. For PUCCH formats 2, 2a, 2b and normal cyclic prefix

${h\left( {n_{CQI},n_{HARQ}} \right)} = \left\{ \begin{matrix}{10{\log_{10}\left( \frac{n_{CQI}}{4} \right)}} & {{{if}\mspace{14mu} n_{CQI}} \geq 4} \\0 & {otherwise}\end{matrix} \right.$

c. For PUCCH format 2 and extended cyclic prefix

${h\left( {n_{CQI},n_{HARQ}} \right)} = \left\{ \begin{matrix}{10{\log_{10}\left( \frac{n_{CQI} + n_{HARQ}}{4} \right)}} & {{{{if}\mspace{14mu} n_{CQI}} + n_{HARQ}} \geq 4} \\0 & {otherwise}\end{matrix} \right.$

SUMMARY

As mentioned above, one of the transmit power control parameters—i.e.,h(n_(CQI),n_(HARQ)) is defined for various PUCCH formats supported inRel-8. Furthermore, it has been proposed for the PUCCH format 3 inRel-10 to apply h(n_(CQI),n_(HARQ))=10 log₁₀(n_(HARQ)). However, thecurrently proposed logarithmic value of h(n_(CQI),n_(HARQ)) for thePUCCH format 3 may not provide accurate power control.

Therefore, it is desirable to have a better determination ofh(n_(CQI),n_(HARQ)) for both of the CA PUCCH formats in Rel-10 (i.e.,PUCCH format 3 and channel selection) so as to retain the same energyper information bit transmitted through the PUCCH signal (from UE). Itis further desirable to provide a methodology to determine values forthe power control parameter Δ_(F) _(—) _(PUCCH)(F) for PUCCH format 3 inRel-10 to facilitate more accurate power control of uplinktransmissions.

The present invention provides a solution to the above-mentioned need todetermine h(n_(CQI),n_(HARQ)) more accurately for the two CA PUCCHformats in Rel-10. In one embodiment of the present invention,h(n_(CQI),n_(HARQ)) is based on a linear function of n_(HARQ) for bothof the CA PUCCH formats in Rel-10. Based on the CA PUCCH formatconfigured for the UE, the eNB may instruct the UE (e.g., via the TPCbit field in the PDCCH signal from the eNB) to select or apply aspecific linear function of n_(HARQ) as a value for the power controlparameter h(n_(CQI),n_(HARQ)), so as to enable the UE to more accuratelyestablish transmit power of its PUCCH signal. The present invention alsoprovides exemplary values for the parameter Δ_(F) _(—) _(PUCCH)(F) to beused for the PUCCH format 3 in Rel-10.

In one embodiment, the present invention is directed to a method ofcontrolling transmit power of a PUCCH signal to be transmitted by a UEin wireless communication with a processor via a wireless networkassociated therewith. The method comprises: using the processor,configuring a PUCCH format for the PUCCH signal; and using theprocessor, instructing the UE to apply only a linear function ofn_(HARQ) as a value for h(n_(CQI), n_(HARQ)), wherein h(n_(CQI),n_(HARQ)) is a power control parameter based on the PUCCH format andaffecting the transmit power of the PUCCH signal, and wherein n_(CQI)indicates number of Channel Quality Indicator (CQI) bits and n_(HARQ)indicates number of Hybrid Automatic Repeat Request (HARQ) bits in thePUCCH signal.

In another embodiment, the present invention is directed to a mobilecommunication node configured to provide a radio interface to a mobilehandset in a wireless network associated with the mobile handset. Themobile communication node comprises: means for configuring a PUCCHformat for a PUCCH signal to be transmitted by the mobile handset; andmeans for instructing the mobile handset to apply the following linearfunction of n_(HARQ) as a value for h(n_(CQI), n_(HARQ)):

${{h\left( {n_{CQI},n_{HARQ}} \right)} = {\frac{n_{HARQ}}{\alpha} + \beta}},$wherein “α” is an integer constant and |β|<1, wherein h(n_(CQI),n_(HARQ)) is a power control parameter based on the PUCCH format andaffecting the transmit power of the PUCCH signal, and wherein n_(CQI)indicates number of CQI bits and n_(HARQ) indicates number of HARQ bitsin the PUCCH signal.

In a further embodiment, the present invention is directed to a systemthat comprises a mobile handset operable in a wireless networkassociated therewith; and a mobile communication node configured toprovide radio interface to the mobile handset in the wireless network.The mobile communication node in the system is further configured toperform the following: determine a PUCCH format for a PUCCH signal to betransmitted by the mobile handset; and instruct the mobile handset toapply only a linear function of n_(HARQ) as a value for h(n_(CQI),n_(HARQ)), wherein h(n_(CQI), n_(HARQ)) is a power control parameterbased on the PUCCH format and affecting the transmit power of the PUCCHsignal, and wherein n_(CQI) indicates number of CQI bits and n_(HARQ)indicates number of HARQ bits in the PUCCH signal.

In another embodiment, the present invention is directed to a methodthat comprises the steps of: using a processor, receiving a powercontrol signal from a mobile communication node to control transmitpower of a PUCCH signal; in response to the power control signal,selecting a linear function of n_(HARQ) as a value for h(n_(CQI),n_(HARQ)) using the processor, wherein h(n_(CQI), n_(HARQ)) is a powercontrol parameter affecting the transmit power of the PUCCH signal, andwherein n_(CQI) indicates number of CQI bits and n_(HARQ) indicatesnumber of HARQ bits in the PUCCH signal; and, using the processor,transmitting the PUCCH signal with the linear function applied theretoso as to partially control the transmit power of the PUCCH signal.

In another embodiment, the invention is directed to a UE operable in awireless network associated therewith. The UE comprises: means forreceiving a power control signal from a mobile communication node tocontrol transmit power of a PUCCH signal to be transmitted by the UE,wherein the mobile communication node is configured to provide a radiointerface to the UE in the wireless network; and means for applying onlya linear function of n_(HARQ) as a value for h(n_(CQI), n_(HARQ)) inresponse to the power control signal, wherein h(n_(CQI), n_(HARQ)) is apower control parameter affecting the transmit power of the PUCCHsignal, and wherein n_(CQI) indicates number of CQI bits and n_(HARQ)indicates number of HARQ bits in the PUCCH signal.

In a further embodiment, the present invention is directed to a methodof controlling transmit power of a PUCCH signal to be transmitted by aUE in wireless communication with a processor via a wireless networkassociated therewith. The PUCCH signal includes a number of CQI bits anda number of HARQ bits. The method comprises the steps of: using theprocessor, determining whether a PUCCH format for the PUCCH signal usestransmit diversity; and, when the PUCCH format is determined to usetransmit diversity, selecting an offset parameter for the PUCCH formatusing the processor, wherein the offset parameter may or may not affectthe value of h(n_(CQI), n_(HARQ)), wherein h(n_(CQI), n_(HARQ)) is apower control parameter based on the PUCCH format and wherein the offsetparameter affects the transmit power of the PUCCH signal, and whereinn_(CQI) indicates the number of CQI bits and n_(HARQ) indicates thenumber of HARQ bits in the PUCCH signal.

In another embodiment, the present invention is directed to a UEoperable in a wireless network associated therewith. The UE comprises:means for receiving a PUCCH format for a PUCCH signal to be transmittedby the UE, wherein the PUCCH format uses transmit diversity and whereinthe PUCCH signal includes a number of CQI bits and a number of HARQbits; and means for selecting an offset parameter for the PUCCH format,wherein the offset parameter may or may not affect the value ofh(n_(CQI), n_(HARQ)), wherein h(n_(CQI), n_(HARQ)) is a power controlparameter based on the PUCCH format and wherein the offset parameteraffects the transmit power of the PUCCH signal, and wherein n_(CQI),indicates the number of CQI bits and n_(HARQ) indicates the number ofHARQ bits in the PUCCH signal.

In a further embodiment, the present invention is directed to a mobilecommunication node configured to provide a radio interface to a mobilehandset in a wireless network associated with the mobile handset. Themobile communication node comprises: means for determining whether aPUCCH format for a PUCCH signal to be transmitted by the mobile handsetuses transmit diversity, the PUCCH signal including a number of CQI bitsand a number of HARQ bits; and, when the PUCCH format is determined touse transmit diversity, means for selecting an offset parameter for thePUCCH format, wherein the offset parameter may or may not affect thevalue of h(n_(CQI), n_(HARQ)), wherein h(n_(CQI), n_(HARQ)) is a powercontrol parameter based on the PUCCH format and wherein the offsetparameter affects the transmit power of the PUCCH signal, and whereinn_(CQI) indicates the number of CQI bits and n_(HARQ) indicates thenumber of HARQ bits in the PUCCH signal.

The linear determination of h(n_(CQI),n_(HARQ)) (and resulting valuesfor Δ_(F) _(—) _(PUCCH)(F)) according to the teachings of the presentinvention may provide a more accurate power control for the two PUCCHformats in Rel-10—i.e., PUCCH format 3 and channel selection—compared toif the same method as for PUCCH format 2 (i.e., logarithmicdetermination) is adopted. More accurate power control may lead to lessinter-cell interference and high multiplexing capability on PUCCH, andtherefore also higher system throughput (i.e., data throughput indownlink for a UE) on PDSCH (Physical Downlink Shared Channel).

BRIEF DESCRIPTION OF THE DRAWINGS

In the following section, the invention will be described with referenceto exemplary embodiments illustrated in the figures, in which:

FIG. 1 illustrates the principle of Component Carrier (CC) aggregation;

FIG. 2 is a diagram of an exemplary wireless system in which PUCCH powercontrol according to the teachings of one embodiment of the presentinvention may be implemented;

FIG. 3 illustrates graphs depicting operating Signal-to-Noise Ratios(SNRs) for PUCCH format 3 under different channel model assumptions;

FIG. 4 depicts relative operating SNR increments for PUCCH format 3under different channel model assumptions shown in FIG. 3;

FIG. 5 shows that the same linear function for h(n_(CQI),n_(HARQ))disclosed with reference to FIG. 4 can be used to power control channelselection based HARQ feedback schemes;

FIG. 6 shows relative operating SNR plots for two channel selectionfeedback designs having different DTX detection thresholds;

FIG. 7 illustrates simulated results for the link-level performance ofSpatial Orthogonal-Resource Transmit Diversity (SORTD) for PUCCH format3 with the ACK/NACK payload size from 2 to 11 bits;

FIG. 8 illustrates simulated results for the link-level performance ofSORTD for PUCCH format 3 with the ACK/NACK payload size from 2 to 21bits;

FIG. 9 depicts relative operating SNR increments for PUCCH format 3(with transmit diversity) under different channel model assumptionsshown in FIG. 7 and also illustrates that the same linear function forh(n_(CQI),n_(HARQ)) initially disclosed with reference to FIG. 4 can beused to power control a PUCCH format 3 signal with transmit diversity;

FIG. 10 depicts relative operating SNR increments for PUCCH format 3(with transmit diversity) under different channel model assumptionsshown in FIG. 8 and also illustrates that how the linear function forh(n_(CQI),n_(HARQ)) initially disclosed with reference to FIG. 4 fitsthe PUCCH plots with transmit diversity;

FIG. 11 also illustrates relative operating SNR increments for PUCCHformat 3 (with transmit diversity) under different channel modelassumptions shown in FIG. 8, but shows that a linear function forh(n_(CQI),n_(HARQ)) having a slope of ⅓ may provide a better powercontrol for PUCCH plots (with transmit diversity) in FIG. 8;

FIG. 12 is a block diagram of an exemplary mobile handset or UE 12according to one embodiment of the present invention; and

FIG. 13 is a block diagram of an exemplary eNodeB according to anexemplary embodiment of the present invention.

DETAILED DESCRIPTION

In the following detailed description, numerous specific details are setforth in order to provide a thorough understanding of the invention.However, it will be understood by those skilled in the art that thepresent invention may be practiced without these specific details. Inother instances, well-known methods, procedures, components and circuitshave not been described in detail so as not to obscure the presentinvention. Additionally, it should be understood that although theinvention is described primarily in the context of a cellulartelephone/data network, the invention can be implemented in other formsof wireless networks as well (for example, a corporate-wide wirelessdata network, a satellite communication network, and the like).

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, theappearances of the phrases “in one embodiment” or “in an embodiment” or“according to one embodiment” (or other phrases having similar import)in various places throughout this specification are not necessarily allreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments. Furthermore, depending on the context ofdiscussion herein, a singular term may include its plural forms and aplural term may include its singular form.

It is noted at the outset that the terms “coupled,” “connected”,“connecting,” “electrically connected,” etc., are used interchangeablyherein to generally refer to the condition of being electricallyconnected. Similarly, a first entity is considered to be in“communication” with a second entity (or entities) when the first entityelectrically sends and/or receives (whether through wireline or wirelessmeans) information signals (whether containing voice information ornon-voice data/control information) to the second entity regardless ofthe type (analog or digital) of those signals. It is further noted thatvarious figures (including component diagrams, graphs, or charts) shownand discussed herein are for illustrative purpose only, and are notdrawn to scale.

FIG. 2 is a diagram of an exemplary wireless system 10 in which PUCCHpower control according to the teachings of one embodiment of thepresent invention may be implemented. The system 10 may include a mobilehandset 12 that is in wireless communication with a carrier network 14of a wireless service provider through a communication node 16 of thecarrier network 14. The communication node 16 may be, for example, abase station in a 3G network or an evolved Node-B (eNodeB) when thecarrier network is a Long-Term Evolution (LTE) network, and may provideradio interface to the mobile handset 12. In other embodiments, thecommunication node 16 may also include a site controller, an accesspoint (AP), or any other type of radio interface device capable ofoperating in a wireless environment. It is noted here that the terms“mobile handset,” “wireless handset,” and “user equipment (UE)” may beused interchangeably herein to refer to a wireless communication devicethat is capable of voice and/or data communication via a wirelesscarrier network. Some examples of such mobile handsets include cellulartelephones or data transfer equipments (e.g., a Personal DigitalAssistant (PDA) or a pager), smartphones (e.g., iPhone™, Android™,Blackberry™, etc.), computers, or any other type of user devices capableof operating in a wireless environment. Similarly, the terms “wirelessnetwork” or “carrier network” may be used interchangeably herein torefer to a wireless communication network (e.g., a cellular network)facilitating voice and/or data communication between two user equipments(UE's).

In addition to providing air interface (e.g., as represented by awireless link 17 in FIG. 2) to the UE 12 via an antenna 19, thecommunication node 16 may also perform radio resource management (as,for example, in case of an eNodeB in an LTE system) such as, forexample, via Carrier Aggregation (CA) (e.g., aggregation of up to fivecarriers each having a bandwidth of up to 20 MHz) mentionedhereinbefore. In case of a 3G carrier network 14, the communication node16 may include functionalities of a 3G base station along with some orall functionalities of a 3G Radio Network Controller (RNC) to performthe PUCCH power control discussed hereinbelow. Communication nodes inother types of carrier networks (e.g., 4G networks and beyond) also maybe configured similarly. In one embodiment, the node 16 may beconfigured (in hardware, via software, or both) to implement the PUCCHpower control as discussed herein. For example, when existing hardwarearchitecture of the communication node 16 cannot be modified, the PUCCHpower control methodology according to one embodiment of the presentinvention may be implemented through suitable programming of one or moreprocessors (e.g., processor 95 (or, more particularly, processing unit99) in FIG. 13) in the communication node 16. The execution of theprogram code (by a processor in the node 16) may cause the processor toperform PUCCH power control as discussed herein. Thus, in the discussionbelow, although the communication node 16 may be referred to as“performing,” “accomplishing,” or “carrying out” a function or process,it is evident to one skilled in the art that such performance may betechnically accomplished in hardware and/or software as desired.Similarly, the UE 12 may be suitably configured (in hardware and/orsoftware) to perform its portion of PUCCH power control as discussed inmore detail hereinbelow.

The carrier network 14 may include a core network 18 coupled to thecommunication node 16 and providing logical and control functions (e.g.,subscriber account management, billing, subscriber mobility management,etc.) in the network 18. In case of an LTE carrier network, the corenetwork 18 may be an Access Gateway (AGW). Regardless of the type ofcarrier network 14, the core network 18 may function to provideconnection of the UE 12 to other mobile handsets operating in thecarrier network 14 and also to other communication devices (e.g.,wireline phones) or resources (e.g., an Internet website) in other voiceand/or data networks external to the carrier network 14. In that regard,the core network 18 may be coupled to a packet-switched network 20(e.g., an Internet Protocol (IP) network such as the Internet) as wellas a circuit-switched network 22 such as the Public-Switched TelephoneNetwork (PSTN) to accomplish the desired connections beyond the devicesoperating in the carrier network 14. Thus, through the communicationnode's 16 connection to the core network 18 and the handset's 12 radiolink with the communication node 16, a user of the handset 12 maywirelessly (and seamlessly) access many different resources or systemsbeyond those operating within the carrier network 14 of an operator.

As is understood, the carrier network 14 may be a cellular telephonenetwork in which the UE 12 may be a subscriber unit. However, asmentioned before, the present invention is operable in othernon-cellular wireless networks as well (whether voice networks, datanetworks, or both). Furthermore, portions of the carrier network 14 mayinclude, independently or in combination, any of the present or futurewireline or wireless communication networks such as, for example, thePSTN, or a satellite-based communication link. Similarly, as alsomentioned above, the carrier network 14 may be connected to the Internetvia its core network's 18 connection to the IP (packet-switched) network20 or may include a portion of the Internet as part thereof.

Whether Carrier Aggregation (CA) is present or not, during initialaccess, an LTE Rel-10 terminal (or UE) may behave similar to an LTERel-8 terminal. Upon successful connection to the network, the terminalmay—depending on its own capabilities and the network—be configured withadditional CCs in the UL and DL. This configuration may be based onRadio Resource Control (RRC) signaling. However, due to the heavysignaling and rather slow speed of RRC signaling, a terminal may beinitially configured (by the eNB 16) with multiple CCs even though notall of them are currently used. If the terminal/UE 12 is configured onmultiple CCs, the terminal may have to monitor all configured DL CCs forPDCCH and Physical Downlink Shared Channel (PDSCH). This may require awider bandwidth, higher sampling rates, etc., which may result in highpower consumption at the UE 12.

To mitigate above problems with configurations on multiple CCs, LTERel-10 also supports activation of CCs (on top of the configuration ofCCs mentioned above) by the eNB 16. In one embodiment, the terminal orUE 12 monitors only configured and activated CCs for PDCCH and PDSCH. Inone embodiment, activation may be based on Media Access Control (MAC)control elements, which may be faster than RRC signaling. The MAC-basedactivation/de-activation can follow the number of CCs that is requiredto fulfill the current data rate needs. Upon arrival of large dataamounts, multiple CCs are activated (e.g., by eNB 16), used for datatransmission, and de-activated if not needed anymore. All but one CC—theDL Primary CC (DL PCC)—can be de-activated. Activation thereforeprovides the possibility to configure multiple CCs but only activatethem on as-needed basis. Most of the time, a terminal or UE 12 wouldhave one or very few CCs activated, resulting in a lower receptionbandwidth and thus reduced battery consumption.

However, if MAC signaling (and, especially, the HARQ feedback signaling(by the UE 12) indicating if the activation command has been receivedsuccessfully) produces errors, then, in one embodiment, the CA PUCCHformat may be based on the number of configured CCs. Thus, in case ofmore than one CC configured for the UE 12, the CA PUCCH format of Rel-10may be selected for that UE 12 by the eNB 16 and communicated to the UE12 via a downlink control signal (e.g., the PDCCH signal). On the otherhand, in case of configuration of a single CC for the UE 12, a PUCCHformat of Rel-8 may be selected.

From a UE perspective, both symmetric and asymmetric uplink/downlink(UL/DL) CC configurations may be supported. When the UE 12 is configuredwith a single DL CC (which is then the DL PCC) and UL CC (which is thenthe UL PCC), the eNB 16 may instruct the UE 12 to operate dynamicACK/NACK on PUCCH according to Rel-8. The first Control Channel Element(CCE) used to transmit PDCCH for the DL assignment determines thedynamic ACK/NACK resource on Rel-8 PUCCH. If only one DL CC iscell-specifically linked with the UL PCC, no PUCCH collisions may occursince all PDCCH are transmitted using different first CCE.

In cell asymmetric CA scenario or for other reasons, multiple DL CCs maycell-specifically linked with the same UL CC. Terminals configured withsame UL CC but with different DL CC (i.e., with any of the DL CCs thatare cell-specifically linked with the UL CC) share the same UL PCC buthave different DL PCCs. Terminals receiving their DL assignments fromdifferent DL CCs may transmit their HARQ feedback on the same UL CC. Itis up to eNB scheduler (not shown in FIG. 2, but shown in FIG. 13) toensure that no PUCCH collisions occur. However, at least in Rel-10, aterminal may not be configured with more UL CC than DL CC.

In one embodiment, when the UE 12 has multiple DL CCs configuredtherefor (by the eNB 16), each PDCCH transmitted on the DL PCC has aRel-8 PUCCH resource reserved on the UL PCC. Even though a terminal isconfigured with multiple DL CCs, but only receives a DL PCC assignment,it may still use the Rel-8 PUCCH resource on UL PCC. An alternativeembodiment may use, even for a single DL PCC assignment, the CA PUCCHthat enables feedback of HARQ bits corresponding to the number ofconfigured CCs—even though only the DL PCC is active and used. Inanother embodiment, upon reception of DL assignments on a singleSecondary CC (SCC) or reception of multiple DL assignments, CA PUCCH maybe used since CA PUCCH may support feedback of HARQ bits of multipleCCs.

Power control for PUCCH is described in section 5.1.2.1 in Release 10 of3GPP TS 36.213 (mentioned hereinbefore). The disclosure of that sectionis incorporated herein by reference in its entirety. As is known, thepower control for PUCCH contains a general part for all PUCCH formatsand specific parameters that are based on the payload on PUCCH. Thespecific part primarily contains the two parameters Δ_(F) _(—)_(PUCCH)(F) and h(n_(CQI),n_(HARQ)). The parameter Δ_(F) _(—)_(PUCCH)(F) defines the relative performance difference between PUCCHformat 1a and the currently-used PUCCH format (for the UE 12). For PUCCHformat 3 in Rel-10, 3 to 4 different values (as discussed below) may bedetermined for this relative offset. These values may cover potentialdifferent eNB receiver implementations. The parameterh(n_(CQI),n_(HARQ)), on the other hand, adapts the PUCCH transmit power(at the UE 12) to the number of bits that are transmitted in the PUCCHsignal from the UE 12. As given in the “Background” section above, forPUCCH 1a/1b, the value of h(n_(CQI),n_(HARQ)) is 0 dB, since theseformats only support one/fixed payload size (1 or 2-bit ACK/NACK) forthe format. PUCCH format 3 in Rel-10 is however similar to PUCCH format2 in Rel-8 in that it supports different (variable) payload sizes. It istherefore desirable that the power control be adaptable based on thenumber of ACK/NACK bits that are transmitted with PUCCH format 3.

FIG. 3 illustrates graphs 30-35 depicting operating SNRs(Signal-to-Noise Ratio) for PUCCH format 3 under different channel modelassumptions. The values of operating SNRs for PUCCH format 1a (1-bitACK/NACK) for the assumed channel models are also shown as a referenceand identified by the reference numeral “37.” For ease of illustration,each geometrical symbol 38-43 depicted for the SNR values for format 1ais not identified individually in FIG. 3, but collectively identifiedthrough reference numeral “37”. However, each of the geometrical symbols38-43 is identified in the legend section of FIG. 3 and also marked onthe corresponding graph 30-35. It is noted here that the plots 30-35 and37 are simulation results of PUCCH signals received at an eNB (e.g., theeNB 16) under six different assumed radio channel types (i.e.,pedestrian or vehicular channels) and velocities (of UE's in thecorresponding channel type): (i) an Enhanced Pedestrian Channel (EPA)having 10 MHz bandwidth and 3 km/hr UE velocity (i.e., the velocity ofthe UE when the UE is carried by a pedestrian) (identified by a sidewaystriangle 38); (ii) an Enhanced Typical Urban (ETU) channel having 5 MHzbandwidth and 3 km/hr UE velocity (identified by an “x” mark 39); (iii)a 5 MHz ETU channel with 120 km/hr UE velocity (i.e., the velocity ofthe UE when the UE is carried by a vehicle) (identified by a diamondshape 40); (iv) a 10 MHz EPA channel with 3 km/hr UE velocity andpresence of an additional uplink signal—the Sounding Reference Signal(SRS)—from the UE to the eNB (identified by a circle 41); (v) a 5 MHzETU channel with 3 km/hr UE velocity and presence of an SRS signal(identified by an upward triangle 42); and (a 5 MHz ETU channel with 120km/hr UE velocity and presence of an SRS signal (identified by adownward triangle 43).

It is noted here that an SRS signal may be sent by an UE (e.g., the UE12) to an eNB (e.g., the eNB 16). The UE may use the SRS signal to allowthe eNB to provide channel-dependent (i.e., frequency selective) uplinkscheduling. In response to the SRS signal from the UE, the eNB mayprovide the requested scheduling information via PDCCH/PDSCH signalingfrom the eNB. The SRS signal may be sent independently of the PUCCHsignal.

It is observed from FIG. 3 that the shortened PUCCH format 3 (which islimited to a maximum of 11 ACK/NACK bits as opposed to 21 ACK/NACK bitsin FIG. 4 discussed below) may cause small SNR offsets for eachadditional payload (ACK/NACK) bit. With average offset size less than0.3 dB, an additional PUCCH power control term (e.g., in the context ofequation (1)) accounting for SRS subframes explicitly may not bewarranted in PUCCH format 3 signals.

FIG. 4 depicts relative operating SNR increments for PUCCH format 3under different channel model assumptions shown in FIG. 3. To be able todetermine Δ_(F) _(—) _(PUCCH)(F) and the correct function ofh(n_(CQI),n_(HARQ)) for PUCCH format 3 in Rel-10, it is assumed in thecontext of FIG. 4 that an eNB (e.g., the eNB under simulation, or theeNB 16 in a real life implementation) can correctly control the power ofPUCCH format 1a. With that assumption, it is desirable to fit acurve/plot that matches the slope of all the different plots 30-35 inFIG. 3 so as to determine a value for h(n_(CQI),n_(HARQ)) in theembodiments of FIGS. 3-4. Determining Δ_(F) _(—) _(PUCCH)(F) may be donein the same process by calculating the difference between PUCCH format1a and the corresponding PUCCH format 3 graphs for each channel type andvelocity.

To construct FIG. 4, each plot 30-35 in FIG. 3 (including the PUCCHformat 1a results 37) has been arbitrary moved so that all the plots layon top of each other. This process thus enables one to find the slope ofall the plots when fitted together, thereby determiningh(n_(CQI),n_(HARQ)). Based on the determination of h(n_(CQI),n_(HARQ)),it is then also possible to determine the corresponding Δ_(F) _(—)_(PUCCH)(F) for each channel scenario. Furthermore, in FIGS. 3 and 4,the simulated receiver (e.g., eNB or other base station) may employsuitable DTX (Discontinuous Transmission) detection algorithm. As isknown, with discontinuous transmission, communication between an eNB andUE over a channel does not occur continuously, but may be cycled on andoff as per data transmission requirements. Thus, a DTX-capable channelmay not be continuously active.

It is noted here that, for ease of illustration and clarity, each graphfrom FIG. 3 appearing in FIG. 4 has not been identified individually.Similarly, in other figures (i.e., FIGS. 5-11) discussed herein, whenclarity is needed, detailed identification of various graphs throughreference numerals is avoided. Furthermore, for ease of discussion, thereference numerals 38-43 and corresponding geometrical symbolsassociated with different channel models are used consistentlythroughout FIGS. 3-6 presented herein. Similarly, reference numerals64-66 and corresponding geometrical symbols associated with differentchannel models are used consistently throughout FIGS. 7-11 discussedbelow.

In FIG. 4, the ACK/NACK (also referred to as “A/N”) bit range isexpanded (to up to 21 bits) to cover the previously provided simulationresults (in FIG. 3) for PUCCH format 3 under different channel modelassumptions. In FIG. 4, plot 45 fits reasonably well over other plots(i.e., shifted versions of plots 30-35 from FIG. 3). It is observed fromplot 45 that the following formula may fit the SNR increments very wellfor the plots 30-35 in FIGS. 3-4:

$\begin{matrix}{{h\left( {n_{CQI},n_{HARQ}} \right)} = \frac{n_{HARQ} - 1}{2}} & (2)\end{matrix}$

Furthermore, from the relative positions of PUCCH format 3 and format 1aplots, it is observed that two of the values for Δ_(F) _(—) _(PUCCH)(F)may be 0 and 1 dB. To give some extra implementation margin, anadditional value for Δ_(F) _(—) _(PUCCH)(F) may be 2 dB. The fourthvalue for Δ_(F) _(—) _(PUCCH)(F) may be left as spare (forimplementation-specific determination) and can be utilized in casereal-life SNR evaluation results indicate that there is need to expandthe value range of Δ_(F) _(—) _(PUCCH)(F). It is noted here that, in oneembodiment, RRC signaling may have 2 bits allocated to convey a value ofΔ_(F) _(—) _(PUCCH)(F) for a specific PUCCH format, thereby allowingfour (4) different values to be specified for Δ_(F) _(—) _(PUCCH)(F). Inan alternative embodiment, any length of values (≧0) may be specifiedfor Δ_(F) _(—) _(PUCCH)(F) depending, for example, on the number of bitsreserved for Δ_(F) _(—) _(PUCCH)(F) in a radio signaling protocol.

As mentioned before, it has been proposed for the PUCCH format 3 inRel-10 to apply h(n_(CQI),n_(HARQ))=10 log₁₀(n_(HARQ)). FIG. 4 alsoshows a plot 47 for this log-based formula (which is slightly modifiedby deducting 4.5 dB to provide the closest approximation to graphs 30-35in FIG. 4) for h(n_(CQI),n_(HARQ)). It is seen from the plot 47 that theproposed log-based formula for h(n_(CQI),n_(HARQ)) does not appear tofit the data as well as the linear determination provided in equation(2) above.

Thus, in one embodiment, for PUCCH format 3, the parameter Δ_(F) _(—)_(PUCCH)(F) may consist of the values {0 dB, 1 dB, 2 dB, spare}, and

${h\left( {n_{CQI},n_{HARQ}} \right)} = {\frac{n_{HARQ} - 1}{2}.}$Thus, the values for Δ_(F) _(—) _(PUCCH)(F) according to one embodimentof the present invention provide sufficient implementation-relatedmargin and cover different receiver (i.e., eNB or other base station)implementations. Furthermore, the values for Δ_(F) _(—) _(PUCCH)(F) alsocover different operation scenarios an eNB (e.g., the eNB 16) may bedeployed in (e.g., if the radio environment around the eNB creates avery dispersive channel, etc.). In one embodiment, the value for theparameter h(n_(CQI),n_(HARQ)) may be more generally expressed as:

$\begin{matrix}{{h\left( {n_{CQI},n_{HARQ}} \right)} = {\frac{n_{HARQ}}{\alpha} + \beta}} & (3)\end{matrix}$In the equation (3) above, “α” is an integer constant and |β|<1. Thevalue of “β” could either be included in the h(n_(CQI),n_(HARQ)) (as incase of equation (3) above) or it could be included in Δ_(F) _(—)_(PUCCH)(F). In the context of equation (2), α=2 and β=−½. However,other values for α and β may be possible in other embodiments. Forexample, in the embodiment of FIG. 11 discussed below, α=3 and β=—⅓.

Thus, according to one embodiment of the present invention, the eNB 16may initially configure a PUCCH format for the UE 12. In case of carrieraggregation (CA), the eNB 16 may specify a CA PUCCH format such as PUCCHformat 3 or channel selection. Based on the CA PUCCH format, the eNB 16may instruct the UE 12 to apply only a linear function of n_(HARQ) (asgiven, for example, by equations (2) and (3) above) as a value forh(n_(CQI),n_(HARQ)) to control the transmit power of the PUCCH signal tobe transmitted by the UE 12. In one embodiment, appropriate linearfunctions for h(n_(CQI),n_(HARQ)) may be stored in a memory (shown inFIG. 12) in the UE 12. These functions may address channel conditions,whether transmit diversity is used or not (as discussed below), etc. TheeNB 16 may specify (e.g., via an indication (e.g., a specific value orcombination of bits) through a TPC command in a DCI message on PDCCH) tothe UE 12 which of those stored functions to apply for power control.Similarly, UE 12 may also store a set of values for Δ_(F) _(—)_(PUCCH)(F) as per the teachings of the present invention. The eNB 16may also specify (e.g., via the TPC command) which value for Δ_(F) _(—)_(PUCCH)(F) may be used by a specific UE 12 based on the existingchannel conditions and PUCCH format. The UE 12 may be configured toselect the eNB-specific values for various uplink power controlparameters.

It is here observed that, because all TPC commands address the same ULCC and/or PUCCH reference, in one embodiment, it may be desirable toonly transmit the true TPC command in one TPC field and reuse TPC fieldsin other DCI messages for non-power control related information. Doingthis may enable higher data rates for non-redundant control information.

Referring now to equation (2), if PUCCH format 3 is used for CAACK/NACK, in one embodiment, n_(HARQ) in equation (2) can be based onone or more of the following: (i) the number of ACK/NACK bits (in thePUCCH signal to be transmitted by the UE 12) that corresponds to thenumber of configured component carriers and configured transmissionmodes on the configured CCs; (ii) the number of ACK/NACK bits thatcorresponds to the number of activated component carriers and configuredtransmission modes on the activated CCs; and (iii) the number ofACK/NACK bits that corresponds to the number of transport blocksreceived at the UE 12 (e.g., the number of ACK/NACK bits actually to betransmitted by the UE 12 for the received transport blocks). Thetransmission modes may include various Multiple Input Multiple Output(MIMO) UL/DL transmission modes in LTE.

It is observed here that it may be very seldom that a UE is notscheduled on all resources that it can receive. In other words, if theUE is activated on multiple component carriers and it is scheduled, thenthe UE is in most times scheduled on all its activated componentcarriers. To avoid a situation in which the UE transmits with too lowpower, in one embodiment, it may be desirable that the UE set its poweron PUCCH format 3 based on the number of activated component carriers.

However, if the eNB and UE have different understanding about the numberof activated component carriers, in one embodiment, the value ofn_(HARQ) for PUCCH format 3 may be based on the number of configured CCsand not on the number of activated component carrier. There are mainlytwo aspects here: (i) NACK→ACK or ACK→NACK error in the MAC(de-)activation message in case a component carrier is activated ordeactivated, and (ii) the case with autonomous deactivation of componentcarriers by UE. Autonomous deactivation was introduced in case the eNB“forgets” to deactivate component carriers. Thus, autonomousdeactivation situation could therefore be avoided at the eNB level byappropriate eNB implementation. However, the NACK→ACK or ACK→NACK errorsmay still occur in some situations, but the impact of them may be smallif they only affect the power control compared to the coding partbecause, for the power control, the eNB could compensate by transmittingsome additional TPC commands. Further, if the power control is based onthe number of activated component carriers together with the configuredtransmission modes on these component carriers, the transmitted power ofthe UE may in most cases correspond to the number of scheduled componentcarriers.

On the other hand, if PUCCH format 3 is used for non-CA ACK/NACK,n_(HARQ) in equation (2) above can be based on one or more of thefollowing: (i) the number of ACK/NACK bits that corresponds to themaximum number of possible scheduled DL transport blocks correspondingto utilized UL/DL subframe configuration and configured transmissionmodes for the UE 12; (ii) the number of ACK/NACK bits that correspondsto the maximum number of possible scheduled DL transport blocks withinthe feedback window of the UL subframe where the PUCCH format 3 istransmitted; and (iii) the number of ACK/NACK bits that corresponds tothe number of transport blocks received at the UE 12. In one embodiment,data (to be sent to the eNB 16) may arrive at a coding unit (not shown)in the UE 12 in the form of a maximum of one transport block perTransmit Time Interval (TTI) (which can be equal to a frame duration of1 ms). In all the three above cases, spatial bundling may be performedso that one ACK/NACK bit is at maximum generated per associated DLsubframe.

It is noted here that although n_(HARQ) in equations (2) and (3) may begenerally determined in terms of the number of ACK/NACK bits, in certainembodiments, scheduling requests (SR) could also be taken into accountin the same manner as ACK/NACK bits in determining the value ofn_(HARQ). Thus, in some embodiments, the parameter n_(HARQ) maycorrespond to only the number of ACK/NACK bits, but, in otherembodiments where SR is jointly transmitted together with the ACK/NACK,n_(HARQ) may also account for SRs as well (i.e., in addition to A/Nbits). Furthermore, in some other embodiments, the number of ACK/NACKbits for the value of n_(HARQ) may also take into account anySemi-Persistent Scheduling (SPS) deactivation message from the UE 12.

FIG. 5 shows that the same linear function for h(n_(CQI),n_(HARQ))disclosed with reference to FIG. 4 can be used to power control channelselection (CS) based HARQ feedback schemes, such as those described by3GPP Contribution Document No. R1-105807, “Way forward on A/N mappingtable for channel selection, Nokia Siemens Networks” (referred to hereinas “R1-105807”), which is incorporated by reference herein in itsentirety. As mentioned before, CA PUCCH in Rel-10 can be done in twodifferent ways: (i) the use of PUCCH format 3 (discussed hereinbeforewith reference to FIG. 3-4), or (ii) Channel Selection (CS). The basicprinciple of the second CA PUCCH method—i.e., channel selection—is thatthe UE is assigned a set of PUCCH format 1a/1b resources by the eNB. TheUE then selects one of the assigned resources according to the ACK/NACKsequence (which may include DTX detection bits) the UE should transmit.Once the resource is selected, the UE would then transmit the ACK/NACKsequence using a Quadrature Phase Shift Keying (QPSK) signal or a BinaryPhase Shift Keying (BPSK) signal. The eNB detects which resource the UEuses and which QPSK or BPSK value the UE fed back on the used resource,and combines this detection into an HARQ response for associated DLcells. Thus, the number of A/N bits in the channel selection method ofCA PUCCH may range from 2 to 4 bits as illustrated on the x-axis in FIG.5.

In FIG. 5, similar to FIG. 4, various individual SNR plot simulationsare combined to obtain relative operating SNR increments. For the sakeof clarity and ease of illustration, these plots are collectivelyidentified by the reference numeral “50.” Similarly, data points forPUCCH format 1a are also shown as a reference and identified by numeral“52.” As in case of FIG. 4, the value of

${h\left( {n_{CQI},n_{HARQ}} \right)} = \frac{n_{HARQ} - 1}{2}$(equation (2) above) fits reasonably well in the embodiment of FIG. 5 ascan be seen by the plot 54. FIG. 5 also shows a plot 55 for the proposedlog-based formula for h(n_(CQI),n_(HARQ)) (which is slightly modified bydeducting 3.5 dB to provide the closest approximation to graphs 50 inFIG. 5). Again, similar to the case in FIG. 4, it is seen from the plot55 that the proposed log-based formula for h(n_(CQI),n_(HARQ)) does notappear to fit the data as well as the linear determination provided inequation (2) above.

FIG. 6 shows relative operating SNR plots 56-57 for two channelselection feedback designs having different DTX detection thresholds.For alternative channel selection feedback designs, such as thatprovided in 3GPP Submission Document No. R1-105476, “Mapping Tables forFormat 1b with Channel Selection” (referred to herein as “R1-105476”),which is incorporated herein by reference in its entirety, the DTXdetection threshold of the receiver (i.e., eNB or other BS) can be setnon-uniformly for the range of HARQ feedback bits (which may range from2 to 4 A/N bits as mentioned before). More specifically, two cases areconsidered in the following with reference to the simulated plots 56-57in FIG. 6. (The data points 58 for PUCCH format 1a are also provided asreference.)

(1) The DTX detection threshold of a receiver (e.g., the eNB 16) can beuniformly set to achieve, for instance, Freq(PUCCH DTX→ACK bits)≦10⁻³.The plots 56 FIG. 6 and plots 50 in FIG. 5 represent the CS case inwhich Freq(DTX→ACK)=0.001. As in case of the plots 50 in FIG. 5, thesame linear function h(n_(CQI),n_(HARQ)) (indicated by plot 54) can beused for plots 56 to power control this channel-selection-based HARQfeedback scheme with uniform DTX detection threshold setting. The reasonfor the more stringent DTX detection threshold is that some NACK valuesare mapped to DTX and the likelihood that Pr(NACK→ACK)≦10⁻³.

(2) For the special case of 3 A/N feedback bits, the design of R1-105476provides the flexibility to alternatively set the DTX detectionthreshold to Freq(PUCCH DTX→ACK bits)≦10⁻² since no NACK events aremapped to DTX. Because of this looser detection requirement, theoperating SNR is improved by around 0.75 dB (as seen from the plots 57for A/N=3 bits) when compared to the normal DTX detection settings(i.e., corresponding data points in plots 56 for A/N=3 bits). This SNRoffset can be addressed in two ways: (a) In one embodiment, the 0.75 dBoperating SNR offset can be compensated by the carrier network throughthe TPC command δ_(PUCCH) from an eNB (e.g., the eNB 16). Thus, the eNBmay be configured to provide this SNR offset as part of its PUCCH powercontrol. (b) In another embodiment, an additional automatic adjustmentterm of, e.g., −0.75 dB (or −1 dB), can be inserted into the values ofh(n_(CQI),n_(HARQ)) (e.g., equation (3) given hereinbefore) or Δ_(F)_(—) _(PUCCH)(F) function discussed earlier. In one embodiment, animplementation-based solution may be used to resolve this type of SNRoffset case by TPC command in the eNB.

Thus, it is seen from the simulation results in FIG. 5 (in which theHARQ feedback scheme is based on channel selection table provided inR1-105807) and FIG. 6 (in which HARQ feedback scheme is based on channelselection table provided in R1-105476) that the linear function ofh(n_(CQI),n_(HARQ)) (e.g., as provided in equation (2)) provides betterpower control values for CS-based CA PUCCH than the proposed logarithmicfunction. As mentioned before, in one embodiment, receiver (eNB) DTXdetection for 2 or 4 HARQ bits may be based on Freq(PUCCH DTX→ACKbits)≦10⁻³, whereas, for 3 HARQ bit feedback, receiver DTX detection canbe based on either Freq(PUCCH DTX→ACK bits)≦10⁻³ or Freq(PUCCH DTX→ACKbits)≦10⁻².

In one embodiment, a transmit diversity scheme may be used for PUCCHFormat 3. An example of such transmit diversity scheme is SpatialOrthogonal-Resource Transmit Diversity (SORTD), where the sameinformation is transmitted by eNB on each antenna port (not shown) usingan orthogonal resource. Other potential transmit diversity schemesinclude Alamouti (time and frequency based transmit diversity) andfrequency-switched transmit diversity. As discussed with reference toFIGS. 7 through 11, the linear determination of the PUCCH power controlparameter h(n_(CQI),n_(HARQ)) according to the teachings of the presentinvention may be equally used in case of PUCCH format 3 with transmitdiversity.

FIG. 7 illustrates simulated results for the link-level performance ofSpatial Orthogonal-Resource Transmit Diversity (SORTD) for PUCCH format3 with the ACK/NACK payload size from 2 to 11 bits. On the other hand,FIG. 8 illustrates simulated results for the link-level performance ofSORTD for PUCCH format 3 with the ACK/NACK payload size from 2 to 21bits. Thus, in FIGS. 7 and 8 (and also in FIGS. 9-11 discussed below),the A/N payload varies between 2 and 21 bits. In the embodiments ofFIGS. 7-8 (and also in FIGS. 9-11), receiver DTX detection may be basedon Freq(PUCCH DTX→ACK bits)≦10⁻².

In FIG. 7, plots 60-62 are for channel models with transmit diversity(SORTD). These channel models are represented by graphical symbols (asideways triangle, an “x” mark, and a diamond shape) identified bycorresponding numerals “64”, “65”, and “66.” As before, the simulatedreference data points for PUCCH format 1a (1-bit ACK/NACK, and withtransmit diversity) for these channel models are collectively identifiedby reference numeral “68.” In FIG. 8, similar plots for PUCCH format 3(with transmit diversity) are shown by reference numerals 70 through 72and format 1a (with transmit diversity) data points are identified byreference numeral “74.” Thus, like FIGS. 7-8, plots for format 1a inFIGS. 9-11 (discussed below) also use SORTD in correspondence withrespective plots for format 3 therein (which use transmit diversity aswell).

FIG. 9 depicts relative operating SNR increments for PUCCH format 3(with transmit diversity) under different channel model assumptionsshown in FIG. 7 and also illustrates that the same linear function forh(n_(CQI),n_(HARQ)) initially disclosed with reference to FIG. 4 can beused to power control a PUCCH format 3 signal with transmit diversity.In FIG. 9, payload size varies from 2 to 11 bits, and the relativeplacement of PUCCH format 3 plots 60-62 (from FIG. 7) may beaccomplished in the same manner as that discussed hereinbefore withreference to FIG. 4. It is seen from FIG. 9 that the linear value forh(n_(CQI),n_(HARQ)), as given by equation (2) above and plotted as plot78 in FIG. 9, may fit the PUCCH plots 60-62 better than the suggestedlogarithmic value of h(n_(CQI),n_(HARQ))=10 log₁₀(n_(HARQ)) (which isdepicted by plot 80 and slightly modified by deducting 5 dB to providethe closest approximation to relatively-placed graphs 60-62 in FIG. 9).

FIG. 10 depicts relative operating SNR increments for PUCCH format 3(with transmit diversity) under different channel model assumptionsshown in FIG. 8 and also illustrates that how the linear function forh(n_(CQI),n_(HARQ)) initially disclosed with reference to FIG. 4 (andalso as equation (2)) fits the PUCCH plots 70-72 with transmitdiversity. FIG. 11 also illustrates relative operating SNR incrementsfor PUCCH format 3 (with transmit diversity) under different channelmodel assumptions shown in FIG. 8, but shows that a linear function forh(n_(CQI),n_(HARQ)) having a slope of ⅓ may provide a better powercontrol for PUCCH plots 70-72 in FIG. 8. In FIGS. 10-11, the ACK/NACKpayload size varies from 2 to 21 bits. In FIGS. 10-11, the relativeplacement of PUCCH format 3 plots 70-72 (from FIG. 8) may beaccomplished in the same manner as that discussed hereinbefore withreference to FIG. 4. It is seen from FIG. 10 that the linear value forh(n_(CQI),n_(HARQ)), as given by equation (2) above and plotted as plot82 in FIG. 10, may not be a better fit for the PUCCH plots 70-72 ascompared to the suggested logarithmic value of h(n_(CQI),n_(HARQ))=10log₁₀(n_(HARQ)) (which is depicted by plot 84 and slightly modified bydeducting 4.6 dB to provide the closest approximation torelatively-placed graphs 70-72 in FIG. 10). However, in case of FIG. 11,it is seen that the linear value for h(n_(CQI),n_(HARQ)) (given by

${h\left( {n_{CQI},n_{HARQ}} \right)} = \frac{n_{HARQ} - 1}{3}$and plotted as plot 86 in FIG. 11) may fit the PUCCH plots 70-72 betterthan the suggested logarithmic value of h(n_(CQI),n_(HARQ))=10log₁₀(n_(HARQ)) (which is depicted by plot 88 and slightly modified bydeducting 6.4 dB to provide the closest approximation torelatively-placed graphs 70-72 in FIG. 11).

In the embodiments of FIGS. 7-11, Reed-Muller (RM) code may be used forencoding of PUCCH payload (A/N bits). However, since the single RM codeis only defined for up to 11 bits, in one embodiment, a dual RM-code maybe applied for payload (A/N bits) sizes larger than 11 bit. Thus, due tothe encoder switch at 12 bit, the Signal to Interference-plus-NoiseRatio (SINR) increment may change and a single linear function (as, forexample, in equation (2)) may no longer be the preferred approximation.Thus, as shown in FIG. 9—where the ACK/NACK payload sizes vary between 2and 11 bit—it is seen that the function

${h\left( {n_{CQI},n_{HARQ}} \right)} = \frac{n_{HARQ} - 1}{2}$with slope ½ is a good match. However, in FIG. 10, where the operatingSINR increment from 2 to 21 bits is shown, it can be seen that the sameapproximation

${h\left( {n_{CQI},n_{HARQ}} \right)} = \frac{n_{HARQ} - 1}{2}$may no longer be a good fit. Thus, in FIG. 11, the operating SINRincrement is modeled with the function

${{h\left( {n_{CQI},n_{HARQ}} \right)} = \frac{n_{HARQ} - 1}{3}},$which may provide a better fit.

In one embodiment, the operating SINR increase for PUCCH Format 3 withSORTD (transmit diversity) may be modeled for all ACK/NACK payload sizeswith the same linear function, e.g.,

${h\left( {n_{CQI},n_{HARQ}} \right)} = {\frac{n_{HARQ} - 1}{3}.}$In another embodiment, the operating SINR may be approximated withdifferent functions for h(n_(CQI),n_(HARQ)) depending on the ACK/NACKpayload size, e.g.,

${h\left( {n_{CQI},n_{HARQ}} \right)} = \frac{n_{HARQ} - 1}{2}$may be used for up to 11 A/N bits, and for 12 bits and above

${h\left( {n_{CQI},n_{HARQ}} \right)} = \frac{n_{HARQ} - 1}{3}$may be used. Thus, the eNB 16 may instruct the UE 12 to either apply asingle function or a combination of functions for h(n_(CQI),n_(HARQ))depending on the payload size in the PUCCH format 3 signal (withtransmit diversity) to be transmitted by the UE 12.

In one embodiment, instead of basing the function h(n_(CQI),n_(HARQ))(which may be linear as given by equation (3) above or may be non-linearas the proposed log-based formula for h(n_(CQI),n_(HARQ)) in Rel-10)only on the ACK/NACK payload size, one may also consider if a givenPUCCH format (e.g., PUCCH format 1a, 2, 2a, 3, etc.) uses transmitdiversity or not. Thus, h(n_(CQI),n_(HARQ)) (linear or non-linear) maybe generalized into h(n_(CQI),n_(HARQ),s_(TxD)), where the parameters_(TxD) indicates if transmit diversity is used or not. In case ofpresence of transmit diversity, additional considerations may apply asdiscussed below.

In one embodiment, the operating SINR increase for a given PUCCH format(with transmit diversity) may be relative to the SINR required for PUCCHformat 1a without transmit diversity. If, however, PUCCH format 1a alsouses transmit diversity, the difference between the SINR values forPUCCH format 1a (with transmit diversity) and the given PUCCH format(with transmit diversity) may increase. The function h(n_(CQI),n_(HARQ))(linear or non-linear) may therefore not only depend on if the givenPUCCH format (e.g., PUCCH format 2, 2a, 3, etc.) uses transmitdiversity, but also if PUCCH format 1a uses transmit diversity. In thissituation, up to four different functions for h(n_(CQI),n_(HARQ)) (e.g.,each may be linear in the form given by equation (3) and may have adifferent slope and/or “β” as determined according to the teachings ofthe present invention, or each may be non-linear as in case of theproposed logarithmic function in Rel-10, or there may be a combinationof linear and non-linear functions depending on the given PUCCH format)may be provided for the four cases involving PUCCH format 1awith/without TxD and the given PUCCH format (e.g., PUCCH format 2a, 3,etc.) with/without transmit diversity. These four functions may benetwork-specific and may be stored in a memory (shown in FIG. 12) in theUE 12 prior to UE's operation in the network 14, or, alternatively,these functions may be provided by the eNB 16 (as per networkimplementation) and stored in UE's memory upon UE's 12 initialconnection to the network 14. Depending on its configuration (e.g., withcarrier aggregation, without carrier aggregation, with/without transmitdiversity, etc.), for example, by the eNB 16, in one embodiment, the UE12 may choose one out of these four functions from its memory.

In one embodiment, a new offset parameter (referred to herein as“Δ_(TxD)(F)”), which may be independent of and not part of theh(n_(CQI),n_(HARQ)) function (whether linear or non-linear), may besignaled (e.g., by eNB 16) as a power control parameter for each PUCCHformat that has transmit diversity configured. If UE is configured byhigher layers to transmit PUCCH on two antenna ports (i.e., withtransmit diversity), then the value of Δ_(TxD)(F) may be provided byhigher layers as discussed in 3GPP TS 36.213 (Release 10), where eachPUCCH format “F” is defined in 3GPP TS 36.211: “Evolved UniversalTerrestrial Radio Access (E-UTRA); Physical channels and modulation.” Inone embodiment, for PUCCH format 3 (with transmit diversity), someexemplary values for Δ_(TxD)(F) may be 0 dB and −1 dB as can be observedfrom a comparison of FIGS. 3 and 7. In another embodiment, someexemplary values for Δ_(TxD)(F) may be 0 dB and −2 dB. Equation (4)below is a modified version of equation (1) including this new parameterΔ_(TxD)(F):P _(PUCCH)(i)=min{P _(CMAX) ,P ₀ _(—) _(PUCCH) +PL+h(n _(CQI) ,n_(HARQ))+Δ_(F) _(—) _(PUCCH)(F)+g(i)±Δ_(TxD)(F)}  (4)It is observed here that Δ_(TxD)(F) is shown as a separate parameter inequation (4) and may not affect the value of h(n_(CQI),n_(HARQ)).However, in one embodiment, Δ_(TxD)(F) may be part ofh(n_(CQI),n_(HARQ)) in the overall power control formula and, hence, mayaffect the value of h(n_(CQI),n_(HARQ)).

In one embodiment, if PUCCH format 1a with/without transmit diversityonly influences this new parameter Δ_(TxD)(F), but not the slope of theapproximation for h(n_(CQI),n_(HARQ)) (whether linear or non-linear),then the same value for h(n_(CQI),n_(HARQ)) may be used for a givenPUCCH format (e.g., PUCCH format 2, 2a, 3, etc.) regardless of whetherthis given PUCCH format is with/without transmit diversity, and thisvalue of “h” may be independent of PUCCH format 1a with/without transmitdiversity. In this case, the UE 12 may be configured (e.g., by themanufacturer of the UE 12 or an operator of the network 14) to select avalue for the offset parameter Δ_(TxD)(F), depending on PUCCH Format 1awith/without transmit diversity. In one embodiment, various values ofΔ_(TxD)(F) may be stored in UE's memory. Alternatively, the network 14(e.g., through the eNB 16) may signal the offset (Δ_(TxD)(F)) to the UE12 (e.g., via a DCI message on a PDCCH signal). It is noted here that,in case of transmit diversity, the selection of a value forh(n_(CQI),n_(HARQ)), or, alternatively, for the offset parameterΔ_(TxD)(F), may be UE-specific since the transmit diversityconfiguration is UE-specific. Thus, in contrast to the parameter “β” inequation (3) above, in case of transmit diversity, the offset parameterΔ_(TxD)(F) may not be included in the cell-specific parameter Δ_(F) _(—)_(PUCCH)(F)

It is noted here that although the foregoing discussion (includingdiscussions related to linearity-based determination ofh(n_(CQI),n_(HARQ)), usage of offset parameter Δ_(TxD)(F), etc.) isprovided in the context of SORTD, the same discussion applies for anyother transmit diversity scheme as well. Thus, in one embodiment, thefunction h(n_(CQI),n_(HARQ)) approximating the operating SINR depends iftransmit diversity is used or not. Furthermore, the foregoingdisclosures of determining the value of PUCCH power control parameterh(n_(CQI),n_(HARQ)) as a linear function of n_(HARQ) and usage of theoffset parameter Δ_(TxD)(F) independent of the “h” function are also notlimited to transmit diversity applied to PUCCH Format 3; the disclosuresmay be utilized with any other appropriate PUCCH format as well (whetherused in conjunction with carrier aggregation or not).

FIG. 12 is a block diagram of an exemplary mobile handset or UE 12according to one embodiment of the present invention. The UE 12 mayinclude a transceiver 90, an antenna 91, a processor 92, and a memory94. In particular embodiments, some or all of the functionalitiesdescribed above (e.g., reception of TPC commands from the eNB 16 via theantenna 91 and transceiver 90; storage of appropriate values forh(n_(CQI),n_(HARQ)), Δ_(F) _(—) _(PUCCH)(F), and Δ_(TxD)(F), andselection of specific values as per instructions from the eNB 16;transmission of a PUCCH signal to eNB 16 with desired power control viatransceiver 90 and antenna 91; etc.) as being provided by mobilecommunication devices or other forms of UE may be provided by the UEprocessor 92 executing instructions stored on a computer-readablemedium, such as the memory 94 shown in FIG. 12. Alternative embodimentsof the UE 12 may include additional components beyond those shown inFIG. 12 that may be responsible for providing certain aspects of theUE's functionality, including any of the functionality described aboveand/or any functionality necessary to support the solution describedabove.

FIG. 13 is a block diagram of an exemplary eNodeB (or a similarcommunication node) 16 according to one embodiment of the presentinvention. The eNodeB 16 may include a baseband processor 95 to provideradio interface with the mobile handsets (in the carrier network 14) viaeNodeB's Radio Frequency (RF) transmitter 96 and RF receiver 98 unitscoupled to the eNodeB antenna 19. The processor 95 may be configured (inhardware and/or software) to perform determinations ofh(n_(CQI),n_(HARQ)) and Δ_(F) _(—) _(PUCCH)(F) as per the teachings ofthe present invention and instruct the UE 12 via appropriate downlinksignals (e.g., the PDCCH signal) to apply the determined values as partof UE's power control of the PUCCH signals to be transmitted by the UE12. In one embodiment, the processor 95 may also determine and supplyvalues for the parameter Δ_(TxD)(F) to the UE 12 (e.g., via the PDCCHsignal). In the context of FIG. 13, the transmissions from the UE 12 maybe received at the receiver 98, whereas eNB's transmissions to the UE 12may be carried out via the transmitter 96. The baseband processor 95 mayinclude a processing unit 99 in communication with a memory 102 toprovide the determinations of, for example, h(n_(CQI),n_(HARQ)) andΔ_(F) _(—) _(PUCCH)(F) to the UE 12 as per the teachings of the presentinvention. A scheduler (e.g., the scheduler 104 in FIG. 13) in the eNB36 may provide the scheduling decision for UE 12 based on a number offactors such as, for example, QoS (Quality of Service) parameters, UEbuffer status, uplink channel quality report received from UE 12, UEcapabilities, etc. The scheduler 104 may have the same data structure asa typical scheduler in an eNB in an LTE system.

The processor 95 may also provide additional baseband signal processing(e.g., mobile device registration, channel signal informationtransmission, radio resource management, etc.) as required. Theprocessing unit 99 may include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs), FieldProgrammable Gate Arrays (FPGAs) circuits, any other type of integratedcircuit (IC), and/or a state machine. Some or all of the functionalitiesdescribed above as being provided by a mobile base station, a basestation controller, a node B, an enhanced node B, and/or any other typeof mobile communications node may be provided by the processing unit 99executing instructions stored on a computer-readable data storagemedium, such as the memory 102 shown in FIG. 13.

The eNodeB 16 may further include a timing and control unit 104 and acore network interface unit 105 as illustrated in FIG. 13. The controlunit 104 may monitor operations of the processor 95 and the networkinterface unit 106, and may provide appropriate timing and controlsignals to these units. The interface unit 106 may provide abi-directional interface for the eNodeB 16 to communicate with the corenetwork 18 to facilitate administrative and call-management functionsfor mobile subscribers operating in the carrier network 14 througheNodeB 16.

Alternative embodiments of the base station 16 may include additionalcomponents responsible for providing additional functionality, includingany of the functionality identified above and/or any functionalitynecessary to support the solution described above. Although features andelements are described above in particular combinations, each feature orelement can be used alone without the other features and elements or invarious combinations with or without other features and elements. Themethodology provided herein (related to the determinations ofh(n_(CQI),n_(HARQ)), Δ_(F) _(—) _(PUCCH)(F), and Δ_(TxD)(F)) may beimplemented in a computer program, software, or firmware incorporated ina computer-readable storage medium (e.g., the memory 102 in FIG. 13 andmemory 94 in FIG. 12)) for execution by a general purpose computer or aprocessor (e.g., the processor 92 in FIG. 12 and processing unit 99 inFIG. 13). Examples of computer-readable storage media include a ReadOnly Memory (ROM), a Random Access Memory (RAM), a digital register, acache memory, semiconductor memory devices, magnetic media such asinternal hard disks, magnetic tapes and removable disks, magneto-opticalmedia, and optical media such as CD-ROM disks and Digital VersatileDisks (DVDs).

The foregoing describes a system and method to determine the PUCCH powercontrol parameter h(n_(CQI),n_(HARQ)) more accurately for the two CAPUCCH formats—PUCCH format 3 and channel selection—in LTE Rel-10. In oneembodiment of the present invention, h(n_(CQI),n_(HARQ)) is based on alinear function of n_(HARQ) for both of the CA PUCCH formats in Rel-10.Based on the CA PUCCH format configured for the UE, the eNB may instructthe UE (e.g., via the TPC bit field in the PDCCH signal from the eNB) toselect or apply a specific linear function of n_(HARQ) as a value forthe power control parameter h(n_(CQI),n_(HARQ)), so as to enable the UEto more accurately establish transmit power of its PUCCH signal. Thepresent invention also provides exemplary values for the parameter Δ_(F)_(—) _(PUCCH)(F) to be used for the PUCCH format 3 in Rel-10.Furthermore, a new parameter—Δ_(TxD)(F)—may be signaled for each PUCCHformat that has transmit diversity configured.

The linear determination of h(n_(CQI),n_(HARQ)) (and resulting valuesfor Δ_(F) _(—) _(PUCCH)(F)) according to the teachings of the presentinvention may provide a more accurate power control for the two PUCCHformats in Rel-10 compared to a logarithmic determination. More accuratepower control may lead to less inter-cell interference and highmultiplexing capability on PUCCH, and therefore also higher systemthroughput on PDSCH because higher ACK/NACK throughput in UL may resultin better data throughput in DL for a UE. It is noted here that theteachings of the present invention related to power control of uplinksignaling may be applied, with suitable modifications (as may beapparent to one skilled in the art using the present teachings), toother wireless systems as well—e.g., Wideband Code Division MultipleAccess (WCDMA) systems, WCDMA-based High Speed Packet Access (HSPA)systems, CDMA2000 systems, Global System for MobileCommunications/Enhanced Data Rate for GSM Evolution (GSM/EDGE) systems,and Worldwide Interoperability for Microwave Access (WiMAX) systems.

As will be recognized by those skilled in the art, the innovativeconcepts described in the present application can be modified and variedover a wide range of applications. Accordingly, the scope of patentedsubject matter should not be limited to any of the specific exemplaryteachings discussed above, but is instead defined by the followingclaims.

What is claimed is:
 1. A method in a User Equipment (UE), comprising thesteps of: using a processor, receiving a power control signal from amobile communication node to control transmit power of a Physical UplinkControl Channel (PUCCH) signal, wherein the PUCCH signal includesexactly three Hybrid Automatic Repeat Request (HARQ) bits; wherein thepower control signal provides an offset value in a power controlfunction affecting the transmit power of the PUCCH signal, and whereinthe offset value compensates for an operating signal-to-noise ratio(SNR) improvement that occurs when the mobile communication nodeincreases a Discontinuous Transmission (DTX) detection threshold whenthe PUCCH signal includes exactly three HARQ bits; in response to thepower control signal, lowering the transmit power of the PUCCH signal bythe offset value by applying the offset value-containing power controlfunction to the PUCCH signal using the processor; and using theprocessor, transmitting the PUCCH signal with lower transmit power.
 2. Amethod in a mobile communication node for controlling transmit power ofa Physical Uplink Control Channel (PUCCH) signal to be transmitted by aUser Equipment (UE) in wireless communication with a processor in themobile communication node via a wireless network associated therewith,the method comprising the steps of: using the processor, sending a powercontrol signal to the UE to control transmit power of a Physical UplinkControl Channel (PUCCH) signal that includes exactly three HybridAutomatic Repeat Request (HARQ) bits, wherein including exactly threeHARQ bits in the PUCCH signal enables the mobile communication node toincrease a Discontinuous Transmission (DTX) detection threshold, therebycausing an operating signal-to-noise ratio (SNR) improvement; whereinthe power control signal provides an offset value in a power controlfunction affecting the transmit power of the PUCCH signal, and whereinthe offset value compensates for the operating SNR improvement thatoccurs when the DTX detection threshold is increased; and using theprocessor, instructing the UE to lower the transmit power of the PUCCHsignal by the offset value by applying the offset value-containing powercontrol function to the PUCCH signal to be transmitted by the UE.